1. Field of the Invention
The invention relates to an auxiliary heater for a motor vehicle with a control device for controlling the operation of the auxiliary heater. Furthermore, the invention relates to a motor vehicle with one such auxiliary heater, and a process for control of one such auxiliary heater.
2. Description of Related Art
Heaters of this type are generally used to heat the air of the passenger compartment or to heat the cooling water of an internal combustion engine. In the former case, it is a so-called air heater, in the latter case, a water heater.
In recent years, in vehicles, especially motor vehicles, it has been possible to greatly improve passenger protection. The reason for improvements is essentially that on the one hand it has been possible to detect an accident with electronic aids within milliseconds and on the other to make available active protection systems which instantaneously protect the passengers against the external effects caused by an accident. Active protection systems are mainly automatic belt tighteners and airbags, i.e., inflatable bodies with a pyrotechnic gas generator which exist in the meantime in diverse versions.
German Patent DE 196 15 319 C1 discloses an air conditioning system of a motor vehicle with an evaporator in which, in the case of accident-induced damage to the evaporator, a quick closure closes the air channel which leads from the evaporator to the passenger compartments. The quick closure is preferably a small airbag.
The triggering mechanism for this small airbag can be the same as is used in airbags for passenger protection. However, in this air conditioning system, the actual escape of vapors cannot be prevented.
The object of the invention is to increase passenger protection in motor vehicles which are equipped with an auxiliary heater.
This object is achieved in accordance with the invention in that the initially-mentioned type of auxiliary heater is provided with a control device that detects a signal from at least one motor vehicle safety sensor, uses the signal to detect a safety-critical status of the vehicle, and depending upon this detected state, ceases operation of the auxiliary heater. The object is furthermore achieved with a motor vehicle in which such an auxiliary heater is installed. Finally, the object is also achieved with a process for controlling such an auxiliary heater in a vehicle with the following steps: detecting the safety status of the vehicle and controlling the auxiliary heater depending upon the detected status.
The expression xe2x80x9cvehicle safety sensors,xe2x80x9d within the framework of this specification, encompasses those mechanisms which enable a statement about the safety of the vehicle. They are especially mechanisms which are capable of determining a location, speed and acceleration or braking, rotational or tilting behavior, safety-critical ambient conditions or the status of individual assemblies of the motor vehicle.
The invention is based upon the finding that, in case of an accident of a vehicle with a auxiliary heater, the heater can cause various hazardous conditions. First, there is a danger that a fault will occur in the control of the auxiliary heater, by which the auxiliary heater in an extreme case can become overheated and damaged or destroyed. Furthermore, there is the danger that the flame burning in the auxiliary heater will ignite flammable fuels in the motor vehicle or in the surrounding area of the motor vehicle. This danger is especially high when fuel which is generally highly flammable or explosive has escaped in an accident.
These dangers are averted in the auxiliary heater in accordance with the invention by immediately ceasing the operation of the auxiliary heater upon detection of an accident involving the motor vehicle. In particular, the auxiliary heater is turned off or actuating the heater is prevented. Thus, danger to the passengers of the motor vehicle originating from the auxiliary heater in case of an accident can be prevented.
In accordance with the invention, not only is an accident-induced effect (fire or explosion) on the passengers prevented, but also the accident-induced effect itself is prevented. The major danger in an auxiliary heater originates from the flame burning in the device. By stopping this flame in accordance with the invention, before serious damage to the auxiliary heater can occur due to an accident, it is ensured that the auxiliary heater in the accident does not increase the danger of an explosion as a result of escaped fuel.
In one exemplary embodiment of the invention, the auxiliary heater includes a fuel feed with a shut-off device and the control device is set up to actuate the shut-off device immediately when a safety-critical state is detected. The shut-off device can be, for example, a solenoid valve in a fuel delivery line. Alternatively, or in addition to interrupting the fuel feed in accordance with the invention, the ignition mechanism which is generally present in conventional auxiliary heaters is immediately shut down when an accident is detected.
Even when the fuel supply of the auxiliary heater is ceased, due to so-called afterburning, there is still considerable development of heat, and thus, further danger to the passengers. This hazard is prevented in another exemplary embodiment of the invention in which the auxiliary heater is provided with a combustion air feed and a control device is provided to immediately extinguish the flame in the auxiliary heater by way of the combustion air feed when a safety-critical status is detected.
The safety function of the auxiliary heater in accordance with the invention can be implemented especially economically by setting up the control device of the auxiliary heater to detect the signal of the motor vehicle safety sensor via a control device of the motor vehicle safety system, for example, a belt tightener. These safety systems are often standard equipment in conventional motor vehicles, and therefore, do not lead to additional costs. The control devices with respect to signal exchange are often standardized by so-called interface protocols. Therefore, there is almost no additional cost when the control device of the auxiliary heater developed in accordance with the invention is installed.
To detect an accident of a vehicle which employs the auxiliary heater in accordance with the invention, in an especially economical manner a position sensor, an acceleration sensor and/or an rpm sensor of the motor vehicle can be used. Alternatively, or in addition, the auxiliary heater itself can be provided with one such sensor.
Moreover, the safety of the motor vehicle can be improved by using a tank cap sensor of the motor vehicle as a vehicle safety sensor. The tank cap sensor detects when the vehicle is being refueled, and is therefore in the state during which there is in turn an increased explosion risk.
Exchange of signals between the sensors and the control device of the auxiliary heater can take place especially economically according to one development of the invention via the vehicle data bus which is present anyway in the vehicle.